Structure including jack and mounting therefor



Aug. 9, 1960 E. SUDEROW 2,948,119

STRUCTURE INCLUDING JACK AND MOUNTING THEREFOR Filed Feb. 17, 1955 4 Sheets-Sheet 2 @M%%Ma ATTORNEYS 4 Sheets-Sheet s 1 l N &7///// INVENTOR GEORGE E. SUDEROW ///////////fi//////// m ATTORNEYS Aug. 9, 1960 G. E. SUDEROW STRUCTURE INCLUDING JACK AND MOUNTING THEREFOR Filed Feb. 17, 1955 Aug. 9, 1960 G. E. SUDEROW STRUCTURE INCLUDING JACK AND MOUNTING THEREFOR Filed Feb. 17, 1955 4 Sheets-Sheet 4 INVENTOR GEORGE E summon ATTORNEYS United States Patent STRUCTURE INCLUDING JACK AND MOUNTING THEREFOR George E. Suderow, Staten Island, N.Y., assignor to De Long Corporation, New York, N.Y., a corporation of Delaware Filed Feb. 17, 1955, Ser. No. 483,841

12 Claims. (Cl. 61-46.5)

This invention relates to jack structures of the type shown in the copending application of Robert W. Pointer, Serial No. 283,567, filed April 22, 1952, now Patent 2,775,869, and more particularly to mountings for operating two or more of such jacks in a tandem arrangement. This invention also relates to means for operating caisson-gripping mechanisms of the type shown in the copending application of George E. Suderow, Serial No. 382,948, filed September 29, 1953 and now Patent No. 2,873,580.

In the aforementioned Pointer application, there is disclosed a jack mechanism mountable upon a platform for imparting vertical movements to a tubular platformsupporting caisson that is loosely guided for such movements in a Well extending vertically through such platform. Such jack mechanism comprises two verticallyspaced sections, each including a rigid ring surrounding the caisson and carrying on its inner side one or more hollow annular rubber elements that are constrictible by the introduction of fluid pressure thereinto into string gripping engagement with the caisson. Interposed between the two sections are one or more axially-expansible hollow annular rubber elements that have a bellowslike action and are effective by the introduction of fluid pressure thereinto to force the upper and lower sections away from each other longitudinally of the caisson. Additional means, such as a fluid pressure cylinder, are connected to the two sections for pulling or forcing them toward each other longitudinally of the caisson. Controls are provided for selectively admitting pressure fluid into, and exhausting pressure from, the inflatable elements carried by each section, while the fluid power cylinder is controlled in conventional fashion.

In all of the embodiments shown in the aforementioned Pointer application, the platform is provided with an abutment engageable by the lower section of the jack mechanism to limit downward movement of such section relative to the platform, while additional abutment means are provided on the platform for engagement by the upper section to limit the extent of upward movement thereof relative to the platform. Hence, by means of the cycle of operations described in detail in the Pointer application, the jack mechanism can be operated to forcefully move the caisson step-by-step downwardly or upwardly relative to the platform.

The force developed by each such jack mechanism effective to move a caisson either upwardly or downwardly is limited by the size of the axially-expansible inflatable elements, as well as by the safe limit of pres sure introducible thereinto. Moreover, similar considerations limit to some extent the frictional grip of the upper and lower jack sections on a caisson. Hence, it will be seen that, although a caisson may be capable of safely supporting a given load thereon, a single jack mechanism may not be capable of imposing such a load.

In actual operation of such jack mechanisms, it has been found somewhat difficult to introduce pressure fluid into the axially-expansible elements when the same have Patented Aug. 9,, 1.960

been compeltely collapsed. Additionally, in some modes of operation of such jack mechanism, heavy loads are transmitted through the axially-expansible elements when no pressure is therein and they are completely collapsed. Under such circumstances, it is possible .to damage the axially-expansible rubber elements.

In the aforementioned Suderow application, there is disclosed mechanism, which may be termed a mechanical gripper, which is used in conjunction with a Pointer type jack mechanism for supporting a platform on a caisson independently of the jack. Such mechanical gripper includes a slip ring assembly mounted on the deck of a platform in surrounding relationship with a caisson. The means for setting the slip ring assembly into gripping relationship with the caisson includes a rigid ring having an inner wedgingsurface cooperative with a complementary wedging surface on each of the segments comprising the slip ring assembly for forcefully constricting the assembly by movement .of the ring in one direction longitudinallyof the caisson. The ring is also connected to each of the segments of the assembly so that the latter will be expanded out of gripping engagement with the caisson by movement of the ring in the other direction. The means for moving the ring of the mechanical gripper mechanism disclosed in the Suderow application, however, are relatively complicated and time-consuming in operation.

Accordingly, it is an object of this invention to provide means for mounting two or more jack mechanisms of the type under consideration for tandem operation, to thereby at least double the effective thrusting force of a single jack.

It is another object of this invention to provide a tandem jack and mounting arrangement therefore which will readily accommodate canting. movement of a caisson in its well without effecting a bind between the caisson and the jack mechanism.

It is another object of this invention to provide a relatively simple and inexpensive tandem jack assembly for attachment and detachment as a unitary assembly to and from a platform.

It is another object of this invention to provide meansfor avoiding any difliculty in introducing pressure fluid into the axially-expansible elements of .a Pointer type jack mechanism and also for preventing the imposition of loads on such elements when completely collapsed.

It is a further object of this invention to provide a somewhat simplified operating arrangement for a mechanical gripper.

Other objects and advantages of the invention will be apparent from the following description and accompanying drawings, in which: t

Figure 1 is a vertical view, partially insection of a tandem jack assembly embodying this invention and show ing such assembly mounted on a platform in operative relation to a platform-supporting caisson.

Figure 6 is an elevational view, partly in vertical section, of the structure shown in Figure 5. V

Figure 7 is a vertical sectional view taken substantially on line 7-7 of Figure 6.

Figures 8 to 11 are enlarged fragmentary views of a portion of Figure 1 illustrating the various steps in the operation of the mechanical gripper- Referring now to Figure 1 of the drawings, there is shown a platform 20 having guide means 22 for mounting an elongated platform-supporting member 24 in upright position and for substantially vertical movement relative to the platform. For exemplary purposes, the platform 20 is here shown as a buoyant barge, the supporting member 24 as a tubular caisson, and the guiding means 22 as a well extending through the barge. The well 22 comprises vertically-aligned circular apertures 26 and 28 in the barge deck 30 and bottom plate 32, respectively, which somewhat loosely receive the caisson 24 so as to permit slight canting movements thereof relative to the barge 20, for-reasons later explained. In order to provide such a relatively loose guiding fit, the exterior diameter of the caisson 24 may be, for example, six feet, while thediarneter of the apertures 26 and 28 may be six feet one inch.

The apertures 26 and 28 are suitably reinforced by upper and lower short cylinders or rings 34 and 36 of slightly greater inner diameter than that of the apertures and welded ,to the undersurface of the deck 30 and the inner surface of the bottom plate-3 2, respectively. Extending radially of .the well 22 and welded to the upper ring 34,.the deck 30, and to the interior compartment walls or or bulkheads 38 of the barge 20 which form the well are a plurality of upper vertical stiffener webs 40. Vertical lower webs 42 are similarly welded to the bottom plate 32, and the walls 38. At least four sets of such upper and lower webs 40 and 42 are used in equi-angularly spaced relation and are desirably reinforced by connected inner edge plates 44 and 46, a lower edge plate 48 for the upper web 40, an upper edge plate 50 for the lower Web 42 which extends about the entire well 22, and vertical interconnecting plates 52.

Mounted in superposed relation above the deck 30 in operative relationship with the caisson 24 are two jacks 54 and 56 of the type shown in the aforementioned Pointer application. Since the basic structures of both jacks are identical, a description of the upper jack 54 will sufflce for both. The jack 54 includes an upper gripper section 58 and a lower gripper section 60. The upper gripper section 58 includes an elongated rigid ring or cylinder 62 of greater diameter than that of and surrounding the caisson 24. As best shown in Figure 2, the cylinder 62 is provided with a plurality of uniformly axially-spaced inner circumferential flanges 64 which form a plurality of inwardly-facing channels 66. The inner diameter of the flanges 64 is substantially equal to the diameter of the well apertures 26 and 28. Disposed in each channel 66 is a hollow, annular, inflatable, rubber constricting ring 68, which, when relaxed, has an inner diameter not greater and preferably somewhat less than that of the flanges 64. It will be seen that, when fluid under pressure, such as compressed air, is introduced into the inflatable rings 68, as by a manifold conduit 7 0, they will be constricted into tight gripping engagement with the caisson 24, as shown in Figure 2. Such gripping force is suflicient to enable the gripper section 58 to resist longimendous force.

The upper and lower flanges v64 of the upper grippersection 58 also extend radially outwardly and are spanned by four circumferentially-spaced pairs of longitudinally-- extending reinforcing webs 72 encircled at their lower ends by a short cylinder 74, so that the metal parts of the upper gripper section are formed into a substantially integral unit. The lower gripper section is substantially an inverted duplication of the upper gripper section 58, savethat the outer diameter of the upper flange 76 greater than that of the lower flange 64 of the upper section.

Interposed between the flat annular ends of the upper and lower gripper sections 58 and 68 is a stack of hollow, annular, inflatable, axially-expansible rubber rings 78 separated by flatmetalwasher-like elements 80/ It will be seen that the introduction of fluid under pressure, such as compressed air, into the rings 78 will serve to force the upper and lower gripper sections 58 and 60 of the jack 54 apart, while the exhaust of pressure fluid from such rings Will enable the upper and lower sections of the jack to be moved together. Pressure fluid is introduced into and exhausted from only one of the rings 78 by a conduit 82, while aligned sealed apertures in each element and in the rings adjacent thereto provide communication between all the rings, as shown in Figure 2. The mechanism for moving the two jack sections 58 and 68 toward each other comprises a plurality of piston 84 and cylinder 86 units 88 spaced substantially uniformly about and mounted on the upper gripper section 58. Two rods 90 connect each cylinder 86 to the lower jack section 60, while the piston 84 is secured to the upper jack section 58. Consequently, the introduction of fluid under pressure, via a conduit 92, into the cylinder 86 forcefully moves the two jack sections 58 and 60 toward each other.

Uniformly angularly spaced about the jacks 54 and;

56 are a plurality, here shown as four, vertical I-beams 94 for transmitting tension and compression loads from" the jack 54, and tension loads from the jack 56, to the barge 20, as hereinafter described. Two plates 96 are welded to the opposite sides of the web 98 of each beam 94 at its lower end and depend therefrom to straddle with clearance a corresponding plate 100 which extends through a slot in the deck 38 into a corresponding slot in the web 40 and is weldedto both the deck and the web, as shown in Figures 1 and 4. Extending through oversized aligned apertures in the plates 96 and 100 is a headed pivot pin 102 which preferebaly is secured in place by a headed locking pin 104 extending through apertured legs 106 welded to one of the plates 96. If will be seen that, because the apertures in the plates 96 and 100 are oversized with respect to the diameter of the pivot pin 182, each I-beam 94 not only is mounted for pivotal movement in a plane which includes the axis of the corresponding guide well 22, but also can cant slightly transversely of such plane. Consequently, each beam 94 can cant at least slightly in any direction.

Extending radially inwardly from each beam 94 adjacent its upper end is a downwardly-facing stop or abutment plate 108 which is reinformed by a vertically-extending back-up web or flange 110 and inclined shorter back-up Webs 112, as best shown in Figures 5, 6 and 7.'

The abutment plate 108 is engageable with a corresponding upwardly-facing stop or abutment plate or ear 114 projecting over the cylinder 74 from between a pair of the webs 72pm the upper section 58 of the upper jack 54. The ear 114 is reinforced by depending side back-up plates 116 welded to the cylinder 74 and the flange 6 4, and by a front plate 118 welded to the side plates. A-

connecting pin 120 depends from the abutment plate 108 through anoversized aperture 122 in the ear 114 so as to A reinforcing vertical back-up web or flange for the abutment plate 126 also serves as a back-up web for an upwardly-facing stop or abutment plate 132 on the beam 94 engageable with a downwardly-facing abutment formed by a stop bar or plate 134 secured to the lower jack section 60. The plate 134 depends from the flange 76 and has side back-up webs 136 welded to the cylinder 74 and to thereinforcing webs 72 0f the lower jack section 60. The abutment 134- is reinforced byplates 138 and 140 spanning the webs 136 and 72, respectively. Preferably,

when the upper and lower sections 58 and 60 of the upper jack 54 are separated to their substantially maximumextent by inflation of the rings 78, the abutment plates 108 and 132 on the I-bearns 94 are engaged. by their corresponding stops or abutments 114 and 134 on the jack sections. Means are also provided to constitute a stop or .abutment for the lower section of the lower jack 56 to limit the extent of downward movement thereof relative to the barge 20, but such stop is not mounted on the I-bearns 94 and will be explained in detail hereinafter.

The back-up webs or plates 116 and 118 for the ears 114 and 128 of the upper sections of both jacks 54 and 56 depend downwardly below the lower end of their corresponding jack section and have a stop plate 141 secured thereto. This plate 141 is engageable with the opposite flange 7.6 on the corresponding lower jack section when the two sections of each jack are forced toward eachother. Such engagement takes place just before the axially-expansible rings 78 are completely' collapsed, so that there will be no difliculty in introducing fluid under pressure into such rings and also so that any strong compressive loads exerted by one of the jack sections on the other jack section, when the rings are completely deflated, will be borne by the inter-engagement of the plates 141 with the flanges 76 instead of by the rings 78.

Normally positioned on the deck 30 of the barge 28 about each aperture 26 therein is a segmental slip-ring assembly 142 (Figure 1) substantially identical to that disclosed in the aforementioned Suderow application. The inner side of each segment 144 of the assembly 142 is provided-with a plurality of circumferentially-extending teeth 146 adapted to securely engage and grip the caisson 24 when the assembly is tightly constricted thereabout, as best shown in Figure 3. Each segment 144 of the assembly 142 is also provided with a plurality of outer circumferentially-spaced vertical webs or flanges 150 having inclined outer wedging faces 152 for cooperation with a complementary inclined wedging face 154 on a pressure or slip-operating rigid ring 156. It will be seen that, when the pressure ring 156 is moved downwardly against the slip ring assembly 142, their mutuallywedging faces 154 and 152 will effect construction of the slip ring assembly into tight gripping engagement with the caisson 24. It will be seen that the weight of the barge 20 on the assembly 142, as later explained, will increaseits grip, so that once the assembly is constricted into engagement with the caisson 24, the grip may be termed self-energizing. Preferably, the slip ring asembly '14-2 and ring 156 are also interconnected, as by inclined rods 158 on the assembly engaged with U-shaped lugs 160 on each segment, so that the assembly will be expanded out of gripping engagement with the caisson 24 on upward movement of the ring 156 relative to the slip ring assembly.

Normally, whenever the slip ring assembly 142 is disengaged from the caisson 24 and the two jacks 54 and 56 are to be operated in unison to eflect vertical move ment of the caisson 24 relative to the barge 20, the pressure ring 156 is held in its upper position to disengage the slip ring assembly 142 from the caisson by a circumferential series of handled spacer blocks 162, interposed between the deck 36 of the barge and the undersurface of a lower outer circumerential flange 164 on the pressure ri as shown in Figure 8. When the pressure ring 156 is in this position, its upper surface, formed by an upper outer circumferential flange 166, is directly engageable by the lower end of the lower section of the lowerjack 56, so that the ring 156, together with the spacer blocks 162, serves as an abutment to limit the extent of downward movement of the lower section of the lower jack relative to the barge 20, as also shown in Fig ure 8.

. For practical operation, abarge 28 is equipped with a plurality of caissons 24, wells 22, and jacks and is towed 6. to an erection site with the caissons 24 held up so-that their lower ends project only a slight distance out of the bottoms of their corresponding wells. This is preferably accomplished by the inflation and, consequently, .constriction of the gripper rings 68 of the lower grippersection of the lower jack only, with such section resting on the ring 156 and the latter resting, in turn, on the blocks 162, as shown in Figure 8, to support the weight of the caisson 24. Additionally, when towing the barge, it is desirable for the axially-expansible rings 78 to be inflated to move the upper gripper sections of both jacks upwardly to engage the abutments 114 and 108, and 128 and 126 and place the beams 94 in tension, whereupon the rings 68 of the upper sections of both jacks are inflated in order to securely grip the caisson 24 for an eX- tended portion of its length. Thus the rings 78 tend to prevent canting movements of the caissons 24 in their wells 22 caused by rocking or pitching of the barge 28.

On reaching an erection site, the caissons 24, which may be feet or more in length, are dropped to the bottom by releasing the jacks engaged therewith, such release being effected by exhausting pressure fluid from the gripping rings or elements 68 of both gripper sections of both jacks 54 and 56. When the lower ends of the caissons 24 are engaged with the marine bottom, all of the jacks can then be operated by the cycle of operations set forth more in detail in the aforementioned Pointer application to firmly drive the caissons to refusal into the marine bottom and by further operation of the jacks to lift the barge out of the water on the caissons by a step-by-step movement. In this connection, appropriate controls (not shown) are provided to operate both jacks 54 and 56 of each caisson 24 in unison. During this operation, it will be seen that the weight of the barge will be borne by the plates 100, pivot pins 102, the I-bearns 94, and the abutments or ears 114 and 128 on the latter, for transmission through the jack upper gripper sections to the caisson.

After the barge has been elevated out of the water a desired distance, it usually is desirable to support the barge 20 on the caissons 24 by the mechanical grippers, so that fluid pressure can be exhausted from the several jacks. For this purpose, the barge 20 is supported on the caissons 24 by the upper gripper sections 58 of both jacks 54 and 56, and a plurality of ts-clarnps 168 are applied over the lower outer flange of the lower gripper section of the lower jack 56 and the upper circumferential flange 166 of the pressure ring 156 to connect the two together so that upward movement of the lower gripper section of the lower jack, by its piston and cylinder units 88, will lift the pressure ring and thus enable the spacer blocks 162 to be removed, as shown in Figure 9. The lower gripper section of the lower jack 56 is then moved down by exhausting its units 88 until the pressure ring 156 engages with the slip ring assembly 142 and is supported thereon so that the clamps 168 can be removed. Thereupon, the lower gripper section of the lower jack 56 is lifted by its piston and cylinder units 88 and the spacer blocks 162 are interposed between the upper surface of the pressure ring 156 and the lower end of the lower gripper section of the lower jack 56, as shown in Figure 10.

Pressure fluid is then introduced into the axiallyexpansible rings 78 of the lower jack 56 to force the pressure ring 156 down into constricting engagement with the slip ring assembly 142, to thereby force the latter into tight gripping engagement with the caisson 24. Pressure fluid can then be exhausted from both the upper and lower gripper sections of the upper jack 54 and from the upper gripper section of the lower jack 56 so that the weight of the barge 28 is supported through the I-beam abutments 126 and the abutments 128 on the upper gripper section of the lower jack 56, the axially-expansible rings 78 of the lower jack, the

lower gripper section of the jack 56, the spacer blocks 62, the pressure ring 156, and the slip ring assembly 142 for transmission to the caisson. After the foregoing procedure has been accomplished for all the jacks and caissons, pressure fluid can be bled slowly from the axially-expansible rings 78 of all the lower jacks 56 so that the barge 20 will settle slowly until the stops 141 on the upper sections of the lower jacks 56 are in engagement with the flange 76 of the lower gripper sections, whereupon the weight of the barge will be carried through such stops, as shown in Figure 1. It will be seen that the barge 20 will then be supported entirely on the mechanical grippers without the use of the jacks.

In order to release the mechanical grippers to enable the barge 20 to be lowered back down into the Water by the use of the jacks, as described more in detail in the aforementioned Pointer application, and also to enable the caissons 24 to be pulled up by their jacks so that the barge can be moved to another location, all of the upper and lower jacks are first operated in unison to lift the barge 20 sufiiciently on the caissons 24 so that the lower gripper sections of the lower jacks 56 can be moved up sufllciently by their units 38 to enable the spacer blocks 162 to be removed. Thereupon, the barge is lowered by all the jacks until the spacer blocks 162 can be interposed between the bottom of the pressure ring 156 and the deck 30 of the barge, as shown in Figure 11. The barge is then raised on the caissons by all the jacks to lift the pressure ring 156 relative to the slip ring assembly 142 and thereby cause expansion of the latter out of gripping engagement with the caissons 24. Once this has been accomplished, the barge can then be lowered on the caissons by the jacks as aforesaid.

=It will be seen that, because of the aforementioned loose fit of the caissons 24 in their guiding Wells 22, they will not necessarily fall absolutely straight when dropped to the marine bottom, and will cant somewhat slightly in their Wells. Consequently, if a caisson 24 is canted in its Well 22, when any gripper section of any jack is operated .to grip the caisson, such jack section will tend to center itself relative to the caisson. Such centering can be effected, however, because the various interengageable abutments on the jack sections and the I-beams 94, as well as the interengagement between the lower jack sections and the pressure ring 156, permit the jack sections to move transversely of the caisson in any direction. In this connection, it also will be seen that the oversized apertures 122 also permit such centering action of the upper gripper jack sections. When the various jack sections are so centered relative to a canted caisson, it also is pointed out that each complete jack 54 and 56 will itself be canted relative to the barge 20, and such canted position of the jacks will be permitted by the connections of the I-beams 94 to the barge which permit the I-beams also to cant slightly in any direction and to so accommodate canting movements of the caissons 24. Such canting movements of the caissons 24 are almost essential for effective operation of a barge of the type under consideration, because in rough seas it is almost impossible to drop the caissons, or to jack them down into engagement with the marine bottom, so that such caissons will be absolutely perpendicular with respect to the earth. If the caissons were all tightly guided they would always be parallel, and if they were not dropped perpendicular, it would be impossible to ever level the platform once it had been elevated out of the water. Such leveling procedures are described in copending applications assigned to the assignee of this invention, so a detailed description thereof is unnecessary here.

It thus will be seen that the objects of the invention have been fully and effectively accomplished. It will be realized, however, that the specific embodiment shown and described for the purpose of illustrating the principles of the invention is subject to change without departing from such principles. Therefore, this invention includes all modifications encompassed within spirit and scope of the following claims.

I claim:

1. Jack means for effecting relative movement be-' tween a platform and a substantially upright, elongated;

platform-supporting member guided on the platform for substantially vertical movement therebetween and for limited canting movement in any direction comprising:

at least one pair of upper and lower holding means adapted to be spaced along the length of the member and each independently releasably engageable therewith, symmetrically thereabout against movement relative thereto in said longitudinal directions, and means for forcing said upper and lower holding means selectively away from each other and toward each other in. said longitudinal directions; a plurality of elongated elements adapted to extend generally parallel to the member'and arranged symmetrically about said jack means; means and additional abutment means on each of said elements engageable by said lower holding means for limiting the extent of downward movement thereof relative to the platform.

2. The structure defined in claim 1 in which both of the abutment means provide for limited relative movement between their corresponding holding means and the elements in any direction extending substantially transversely Y of the jack means.

3. Jack means for effecting relative movement between i a platform and a substantially upright, elongated platform-supporting member guided on the platform for substantially vertical movement therebetween and for limited canting movement in any direction comprising: a pair of upper and lower holding means adapted to be spaced along the length of the member and each independently re leasably engageable therewith symmetrically thereabout against movement relative thereto in said longitudinal directions, and means for forcing said upper and lower holding means selectively away from and toward each other in said longitudinal directions; a plurality of elongated tension elements adapted to extend generally paral lel to the member and arranged symmetrically aboutsaid jack means; means for connecting one end of each of said elements to the platform for limited canting movement in any direction; means loosely connecting each of said elements to said jack means for limiting relative movement therebetween in any direction extending trans-- versely of said jack means; abutment means on each of said elements engageable by said upper holding means for limiting the extent of upward movement thereof relative to said elements; and abutment means on the platform engageable by said lower holding means for limiting the extent of downward movement thereof relative to said platform.

4. The structure defined in claim 3 in which both of the abutment means provide for limited movement of, their corresponding holding means relative thereto in any tially upright platform-supporting member for movement relative to the platform in directions extending substantially longitudinally of the member, comprising: at least 9 one pair of upper and lower holding means adapted to be spaced along the length of the member and each independently releasably engageable with the member symmetrically thereabout against longitudinal movement relative thereto; means for forcing said upper and lower holding means selectively away from each other and toward each other longitudinally of the member; a plurality of elongated substantially upright elements arranged symmetrically about said upper and lower holding means, the lower ends of said elements being adapted for connection to the platform to alternatively receive tension and compression loads; means loosely connecting each of said elements to one of said holding means for limiting relative transverse movement therebetween; abutment means on each of said elements engageable by said upper holding means for limiting the extent of upward movement thereof relative to said elements; and additional abutment means on each of said elements engageable by said lower holding means for limiting the extent of downward movement thereof relative to said elements.

7. The structure defined in claim 6 in which the lower end of each element is adapted to be connected to the platform for limited canting movement in any direction.

8. In a structure comprising a platform having guide means thereon for mounting an elongated substantially upright platform-supporting member for movement relative to the platform in directions extending substantially longitudinally of the member, the combination comprising: a segmental slip assembly mounted on the platform for surrounding the member; rigid tubular slip-setting means for surrounding the member; means including interengageable wedging surfaces on said setting means and said assembly efiective to constrict the latter into gripping engagement with the member on relative movement in one direction longitudinally of the member between said setting means and said assembly and to expand said assembly on movement in the other direction; jack means mounted on the platform for eifecting said longitudinal movement of the member comprising a pair of upper and lower holding means spaced along the length of the member and each independently releasably engageable therewith against movement relative thereto in said longitudinal directions, and means for forcing said holding means selectively away from and toward each other in said longitudinal directions; and means for detachably connecting said setting means to said lower holding means for moving the former by the latter in said other assembly-expanding direction.

9. In a structure comprising a platform having a vertical guiding well therethrough for reception of an elongated substantially upright platform-supporting member, the combination comprising: a horizontal plate rigidly secured to the platform and surrounding the well; a segmental slip assembly mounted on said plate for surrounding the member; rigid tubular slip-setting means for surrounding the member; means including interengageable wedging surfaces on said setting means and said assembly effective to constrict the latter into gripping engagement with the member on movement of said setting means toward said plate and to expand said assembly on movement of said setting means away from said plate; jack means for moving the member longitudinally in said well comprising a pair of upper and lower holding means spaced along the length of the member above said setting means and each independently releasably engageable with the member against movement relative thereto longitudinally thereof, and means for forcing said holding means selectively away from and toward each other longitudinally of the member; abutment means on the platform engageable by said upper holding means for limiting the extent of upward movement thereof relative to said platform, said setting means being engageable by said lower holding means on movement thereof toward said plate; and rigid spaced means interposable between said plate and setting means to both maintain the latter in a slip-expanded position and render it effective as an abutment to limit the extent of downward movement of said lower holding means relative to the platform.

10. The structure defined in claim 9 including means for detachably connecting the setting means to the lower holding means to move the former by the latter out of slip-setting engagement with the slip assembly.

11. The structure defined in claim 9 in which the rigid means is also interposable between the lower holding means and the slip-setting means for applying a slipsetting force to the latter by the former.

12. In a structure comprising a platform having guide means thereon for mounting an elongated substantiallyupright platform-supporting member for movement relative to the platform in directions extending substantially longitudinally of the member, and jack means mounted on the platform for selectively effecting or restraining said movement and including a holding means releasably engag'eable with the member against movement in either direction longitudinally thereof and, when released therefrom, movable longitudinally thereof, the combination comprising: a segmental slip assembly mounted on the platform and constrictable into self-energizing gripping engagement with the member for restraining downward movement of the platform relative to the member independently of the jack means; and means for detachably mechanically connecting the holding means to said assembly for moving the latter in a direction to relieve its self-energized grip.

References Cited in the file of this patent UNITED STATES PATENTS 661,470 Fawell et a1 Nov. 6, 1900 1,312,009 Thrift Aug. 5, 1919 1,895,132 Minor Jan. 24, 1933 2,352,370 Carruthers June 27, 1944 2,673,064 Patterson et al Mar. 23, 1954 2,673,065 Patterson Mar. 23, 1954 2,775,869 Pointer Jan. 1, 1957 2,830,788 Bentley et al. Apr. 15, 1958 FOREIGN PATENTS 913,784 Germany June 21, 1954 OTHER REFERENCES 'Ihe'Washington Star Pictorial Magazine, Feb. 7, 1954, pages 12 and 13, 

